Pursuing Zero Net Energy Buildings

Whether for new construction or renovation, early recognition of five key aspects is important.

By Andy Feth, P.E.
From the October 2019 Issue

Zero net energy buildings are at least energy neutral, and ideally produce more energy than they use through a combination of on-site generation and energy efficient measures. This level of sustainability may sound unattainable for your building, but it’s increasingly becoming commonplace as building owners and facility managers realize the return on investment (ROI) of such an investment. Eliminating carbon emissions results in significant environmental benefits and cost savings for building owners and facility managers. It’s true that the upfront cost is more, but short- and long-term savings often make the investment worthwhile.

Zero Net Energy Buildings
Opened in May 2016, Alpine Library is the County of San Diego’s first zero net energy building. An 8.75 kW solar array on the roof provides the site with a renewable energy source. (Photo: C.W. Driver Companies)

Following are five important considerations to recognize when pursuing a zero net energy project:

1. Demand Is High

LEED Silver used to be the gold standard for many owners, but today, instead of being aspired to, this level of certification is almost expected—especially in states like California where CALGreen and Title 24 make a certain level of sustainability a requirement. Now, even the higher level LEED Gold is becoming more popular, and as owners continue to see the ROI of energy efficiency, it’s clear that zero net energy is the next level that many are striving for with their buildings.

California has set the goal of having all new commercial construction and 50% of existing commercial construction zero net energy by 2030, and other states are likely to follow in the coming years. By implementing zero net energy now, building owners and facility managers can stay ahead of the curve.

2. Requires A Holistic Approach

Zero net energy should never be an afterthought. It requires a holistic approach that must be incorporated into all aspects of the planning and construction process—whether it is a new build or renovation. When energy efficient technology is implemented after the fact, it can be much more difficult to incorporate into the building’s design. Having these discussions and doing the necessary calculations up front will help building owners and facility managers take the necessary steps to ensure that the building achieves the desired energy goals.

This holistic approach also increases the likelihood that the energy neutral standard will be exceeded. When excess energy is produced by a zero net energy building, it can be sold to the grid, resulting in an additional income source for the owner and supplemental energy for the surrounding community.

3. Certain Buildings Present Challenges

In buildings that require particularly high energy use, achieving zero net energy can be challenging. But that doesn’t mean it’s impossible. My firm, C.W. Driver Companies, is currently working on a zero net energy project for the County of San Diego’s Assessor/Recorder/County Clerk (ARCC) Office. Because delicate archive materials are housed inside, the building has very strict humidity and temperature requirements. This means that a standalone HVAC system is required rather than a variable refrigerant flow (VRF) system, which is what we’d typically use on a zero net energy project.

Zero Net Energy Buildings
In California, the County of San Diego ARCC Office building design meets LEED Gold and zero net energy specifications. (Photo: C.W. Driver Companies)

In addition to buildings that require high energy usage, sites with limited space for photovoltaic panels and other energy producing systems can also present a significant challenge in achieving zero net energy.

Depending on the unique situation, more limited energy production may be able to be offset by energy saving measures. But of course, there are some situations in which zero net energy isn’t realistic and less ambitious sustainability goals should be explored.

4. The Necessary Technology

There are a wide variety of technologies and energy saving measures that can be employed when pursuing zero net energy. Daylighting, glazing, shading, and window placement can help with temperature control, as can smart use of insulation. Lighting sensors and dimmers can help reduce energy consumption, while photovoltaic cells can help produce the amount of energy necessary to power the building. Photovoltaic cells can be placed on the building’s roof, incorporated into the parking area, or installed on open land, depending on the nature of the site. Solar inverters are necessary to change the electric current from DC to AC, and solar tracking systems help monitor their performance.

Oftentimes, these systems come with tax incentives, and each year these become more affordable to the market as the technology advances.

Reducing water consumption is another way to help reduce energy usage. Low flow faucets and toilets help minimize consumption, as does drought resistant landscaping and graywater for outdoor usage.

At San Diego’s ARCC Building, we installed 3,745 highly efficient photovoltaic cells to power the building’s electrical requirements. We leveraged natural daylight and breezes to maintain comfortable temperatures, and housed the delicate archives within the building’s highly insulated concrete northeast corner of the building.

5. Training Is Imperative

Training on new building systems is one aspect that many building owners and facility managers don’t often consider when pursuing a zero net energy project. The calculations to determine whether zero net energy is feasible are largely based on assumptions about the end user. But if the end user isn’t properly trained on how to regulate energy usage and maintain efficiency, then the benefits of the efficiency measures will not be fully realized in the facility.

When facility management as well as building occupants understand how their choices make a difference, it can shift their habits. For end users, changing the sleep mode setting on computers or adjusting the thermostat so space heaters aren’t necessary can make a significant difference.

Oftentimes, a simple change in mindset is all that’s needed. For example, after C.W. Driver completed a zero net energy project for San Diego’s Alpine Branch Library in California, we noticed that energy usage was much higher than expected. A walkthrough revealed that all of the library’s computers were in full power mode even when they were not in use; a quick change in settings was all that was needed to get the energy calculations back on track so the building could maintain its zero net energy status.

Zero net energy for buildings is becoming more feasible and cost-effective than ever. But it is but it is important for building owners and facility managers to keep these considerations in mind to ensure a zero net energy project is successful.

Zero Net Energy BuildingsFeth is project executive at C.W. Driver Companies, a premier builder serving California since 1919. The company celebrates its 100-year anniversary this year. As a leader in general contracting and construction management services, C.W. Driver Companies is on the cutting edge across a broad spectrum of industries, including education, commercial/office, technology, healthcare/biomedical, mixed-use, assisted living, entertainment, retail, industrial and civic.

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